Prior application Ser. No. 246,939, filed Apr. 24, 1972, now abandoned by William Oroshnik, assigned to assignee of the present application, describes a new process for making Vitamin A carotenoid by-products of Vitamin A, and isomers thereof. One of the intermediates employed in the method of the application is isoprene chloroacetate (4-chloro-3-methylbut-2-enyl acetate) which has the structure ##STR1##
This compound may also be named 1-chloro-4-acetoxy-2-methyl-2-butene or 4-chloro-3-methyl-2-butene-1-yl acetate.
In addition to being useful in making Vitamin A and related products, the isoprene chloroacetate may also be a valuable intermediate in the synthesis of Vitamin E, in the synthesis of carotenoids and in the synthesis of many other terpenic and non-terpenic materials in which isoprene is a basic unit in the molecule.
The synthesis of isoprene chloroacetate is known and is reported in the Journal of the American Chemical Society, Volume 72, page 4608 (1950) in an article by W. Oroshnik and R. A. Mallory. The synthesis involved the treatment of isoprene with tert-butyl hypochlorite in the presence of a large excess of acetic acid. The method suffered from the disadvantages of a relatively low yield of chloroacetate, and of high cost. In addition, the hypochlorite is an unstable material rendering the synthesis difficult.